The magnetophoretic mobility and superparamagnetism of core-shell iron oxide nanoparticles with dual targeting and imaging functionality

Abstract

With the goal to achieve highly efficacious MRI-monitored magnetic targeting, a novel drug carrier with dual nature of superior magnetophoretic mobility and superparamagnetism was synthesized. This carrier was specially designed in a core-shell structure. The core was achieved by utilizing a strategy of self-assembly of oppositely charged ultrafine superparamagnetic iron oxide nanoparticles previously prepared. The final particles were formed by coating such cores with carboxymethyldextran (CMD) polymer. By exclusion of non-magnetic materials from the interior part of the particles, this structure maximized the amount of magnetic material and thus yielded a superior magnetophoretic mobility. Such a strategy avoids the challenge of superparamagnetism loss, which would be caused by cores exceeding a critical domain size. Coating the self-assembled core enables the magnetic carrier to be stable upon usage and storage and to be readily linked with drug molecules for therapeutic applications. In vitro characterization showed that these nanoparticles displayed a 3-to 4-fold enhancement in magnetophoretic mobility, and a markedly improved stability when stored in 50% serum as a comparison of conventional iron oxide-based magnetic nanoparticles. Preliminary in vivo studies revealed that the nanoparticles alsofunction well as a contrast enhancer for MR imaging of brain glioma. This technology could lead to the development of a new paradigm of magnetic carriers that meet with the needs of various clinical applications.

Plasma-assisted synthesis of carbon encapsulated magnetic nanoparticles with controlled sizes correlated to smooth variation of magnetic properties

“…The purified sample corresponding to the lowest pressure (C1WP, 20 mbar), with 56 Oe coercive field and ratio of remnant to saturation magnetization of only 4.9 at 300 K may be considered as approaching the characteristics of super-paramagnetic particles. all measurements [22], in stark contrast to other thermal plasma synthesized magnetic nanomaterials [19]. However, the average size was actually measured from a distribution of sizes with a tail representing bigger particles whose contribution is also inevitably present in the results.…”

“…In order to avoid serious particle agglomeration inside living tissues, the encapsulated nanoparticles should possess superparamagnetic properties, which may be achieved only when the particle is smaller than the ϰ critical domain size. On the other hand, very small particles may be quickly eliminated by the renal filtration system of the living body [22]. Empirically, it has been always observed that saturation magnetization possessed by a CEMN decreases with decreasing encapsulated core particle size, which is an important parameter for proper process control.…”

“…Empirically, it has been always observed that saturation magnetization possessed by a CEMN decreases with decreasing encapsulated core particle size, which is an important parameter for proper process control. The efficiency of magnetic targeting depends on a parameter defined as magnetophoretic mobility, which again can be enhanced only by increasing the size of magnetic materials [22]. Emerging application of carbon stabilized iron nanoparticles in environmental remediation also demands regular shape and narrow size distribution, to ensure dispersion stability of the nanomaterials in waste water [23].…”

Enhanced and selective delivery of enzyme therapy to 9L-glioma tumor via magnetic targeting of PEG-modified, ß-glucosidase- conjugated iron oxide nanoparticles

“…21 Briefly, samples (about 0.5 mg Fe/mL) were well dispersed in deionized water and placed into a 1 cm × 1 cm quartz cuvette fixed on the inner plate of a Dynal magnetic separator. Next, 10 µL aliquots were withdrawn at preset time points for measurement of iron content using inductively coupled plasma optical emission spectroscopy.…”

Magnetic nanocomposites for biomedical applications

“…It might turn out particularly useful for biomedical in vivo applications in diagnostic applications such as MRI [1] and therapies such as sitespecific drug delivery [2,3] and magnetic particle hyperthermia [4,5]. MCNCs, in a form of microparticles (or microspheres), with embedded magnetic cores are especially proposed for in vitro applications [6,7] e.g.…”